The Atlantic cod, Gadus
morhua, is a demersalgadoid species found on both sides
of the North Atlantic. In the Northwest Atlantic cod occur from
Greenland to North Carolina. In U.S. waters, cod are assessed
and managed as two stocks: Gulf of Maine, and Georges Bank and
1.1). Both stocks support important commercial and recreational
fisheries. Commercial fisheries are conducted year round, primarily
with otter trawls and gill nets. Recreational fishing also occurs
year round; peak activity occurs during the late summer in the
lower Gulf of Maine and during late autumn to early spring from
Cod may attain lengths of up to 130 cm (51
in.) and weights of 25 to 35 kg (55 to 77 lb). Maximum age is
in excess of 20 years, although young fish (ages 2 to 5) generally
constitute the bulk of the catch. Sexual maturity is attained
between ages 2 to 4 (O’Brien et al. 1993, O’Brien
1998); spawning occurs during winter and early spring.
Cod are omnivorous, feeding on a variety of invertebrates and fish
species (Lough 2004, O’Brien et al. 2005). Growth rates differ
between the stocks although each is exploited by the same gear types
with similar selection characteristics. Growth of cod in the Gulf
of Maine has historically been slower than on Georges Bank (Pentilla
and Gifford 1976, O’Brien 1998), but appears to have increased
in recent years. Differences in growth rate by sex have also become
less pronounced in both stocks.
United States commercial and recreational
fisheries for cod are managed under the New England Fishery Management
Council's Northeast Multispecies Fishery Management Plan (FMP).
Under this FMP cod are included in a complex of 15 groundfish
species that has been managed by time/area closures, gear restrictions,
and minimum size limits. As well, since 1994, this complex has
been managed using direct effort controls including a moratorium
on permits and days-at-sea restrictions under Amendments 5, 7,
and 13 to the FMP. Trip limits are also in effect for both Gulf
of Maine and Georges Bank cod. Amendment 9 established initial
biomassrebuilding targets (NEFMC 1998) and defined control rules
which specify target fishing mortality rates and corresponding
rebuilding time horizons. Amendment 13 implemented formal rebuilding
plans within specified time frames based on revised biomass and
fishing mortality targets derived by the Working Group on Re-evaluation
of Biological Reference Points for New England Groundfish (NEFSC
2002a). The goal of the management program is to reduce fishing
mortality to levels which will allow stocks within the complex
to initially rebuild above minimum biomass thresholds, and, ultimately,
to remain at or near target biomass levels. In addition, a formal
quota sharing agreement was implemented in 2004 between Canada
and the U.S. to share the harvest of cod in the transboundary
eastern Georges Bank cod management unit. The agreement includes
total allowable catch quotas for each country as well as in-season
monitoring of the U.S. catch of cod on eastern Georges Bank. The
Canadian fishery on Georges Bank is managed under an individual
Total commercial cod landings from the Georges
Bank and Gulf of Maine stocks in 2005 were 6,957 mt, a 17% decrease
from 8,381 mt in 2004. United States commercial landings in 2005
equaled 6,327 mt, 13% less than in 2004 (7,269 mt). Recreational
cod landings totaled 1,585 mt in 2004, a 45% decrease from 2003.
Landings from both stocks remain well below the maxima taken during
the 1970s and 1980s. The information provided herein reflects
the results of the most recent peer-reviewed assessments for the
Gulf of Maine and Georges Bank cod stocks (Mayo and Col 2006,
O’Brien et al. 2006, NEFSC 2005).
Total commerciallandings in
2005 were 3,909 mt, slightly below those from 2001-2003 but approximately
139% greater than in 1999 (Table 1.1,Figure
1.2 Data]). Since 1977, the USA fishery has accounted for all
of the commercial catch. Although otter trawl catches account for
the largest percentage of the landings (averaging between 50 and
59% between 1993 and 2003), the otter trawl fraction has declined
considerably compared to the period prior to 1993. Most of this
change can be attributed to an increase in the percentage of cod
taken by sink gillnets since 1993, although the percentage from
combined handline and line trawls also increased substantially during
the 1990s. The percentage landed by otter trawls declined further
in 2004 to 44%. Discards have also become a significant part of
the commercial catch of Gulf of Maine cod, ranging from 15 to 160
percent of the landings since 1999.
Gulf of Maine cod landings have
generally been dominated by age 3 and 4 fish in numbers (Figure
1.3 Data]). Representation of age 2 cod was relatively high
in the early 1980s but, in response to a series of minimum mesh
size increases during the 1990s, age 2 fish have gradually all but
disappeared from the landings. Cod from the strong 1987 year class
predominated from 1990 through 1992 but, by 1993, fish from the
1990 year class accounted for the greatest proportion of the total
number landed. From 1994 through 1996, landings were dominated by
age 4 cod and in 1997 age 5 fish were dominant, reflecting the higher
abundance of the 1992 year class. Although traditionally low in
terms of their contribution to the total landings, age 10 and 11+
fish were absent for several years during the 1990s, and numbers
of age 8 and 9 fish have also been unusually low. More recently,
the 1998 year class has dominated the landings at ages 3 through
6 in 2001 through 2004, respectively. As well, the proportion of
cod older than age 7 has begun to increase.
and autumn biomass indices for Gulf of Maine cod have generally
exhibited similar trends throughout the survey time series (Figure
1.4 Data]). Total biomass declined during the mid- and late
1960s, but between 1972 and 1985 both have fluctuated as a result
of a series of recruitment pulses. Sharp increases in indices reflect
above-average recruitment of the 1971, 1973, 1977-1980, and 1985-1987
year classes at ages 1 and 2. The sequential dominance of these
cohorts at older ages is evident from number-per-tow-at-age values
in the autumn NEFSC surveys (Figure
1.5 Data]). Increases in the autumn 1994-1995 and spring 1996-1997
biomass indices may be attributed to somatic growth of fish from
the 1992 year class which was the largest in a series of poor year
classes. The survey age composition data reveal a persistent truncation
in the population age structure from about 1985 to 1995 followed
by a period of expanding age structure. More recently, autumn biomass
indices have shown a modest increase, but the large value in 2002
1.4 Data])is the result of a single very large tow that unduly
influenced the calculation of the mean. The 1998 year class is equivalent
to the 1992 year class, and the 2003 and 2004 year classes also
appear to be relatively strong. Biomass indices in 2003-2005 suggest
the population biomass remains slightly above the low level of the
Average fishing mortality (ages 4-5, unweighted)
fluctuated around 1.0 during the 1980s and early 1990s, but steadily
declined thereafter to less than 0.4 in 2002 (Figure
1.6 Data]). Fishing mortality in 2004 was estimated to be
0.58, an increase from 2002 and 2003. The spawning stock biomass
of age 1 and older cod declined from 23,987 mt in 1982 to 15,302
mt in 1987 (Figure
1.7 Data]). Following the recruitment and maturation of the
strong 1987 year class, SSB increased to 24,261 mt in 1990 but
declined to 10,797 mt in 1993, a 3-year reduction of 55%. SSB
increased to 14,996 mt in 1995 due to the growth and maturation
of the 1992 year class, but declined again in 1996 and fell to
11,128 mt in 1997. SSB increased again beginning in 1998, reaching
25,369 mt in 2002, based primarily on growth and maturation of
the 1998 year class. Spawning stockbiomass has since declined
to 20,549 mt in 2004.
Since 1982, recruitment at age 1 has ranged
from less than 4 million fish (1993, 1994, 1995, 2000 and 2002
year classes) to 25.2 million fish (1987 year class (Figure
1.7 Data]). Over the 1982-2004 period, geometric mean recruitment
for the 1981-2003 year classes was 6.3 million fish. The 1987
year class is the highest in the 1982-2004 series and about twice
the size of the next strongest year class. The 1992, 1998 and
2001 year classes were of moderate strength, while the 1993-1995,
1999-2000 and 2002 year classes were weak. The initial estimate
of the strength of the 2003 year class (22 million) is very close
to that of the 1987 year class.
MSY-based reference points were last calculated
by the Working Group on Re-evaluation of Biological Reference
Points for New England Groundfish (NEFSC 2002a) using data and
results from the 2001 assessment (Mayo et al. 2002). A complete
description of the approach is given in Mayo et al. (2002) and
NEFSC (2002a). The MSY-based reference points calculated using
this method are given in Table 1.2.
Gulf of Maine cod spawning stock biomass
has increased since the late 1990s from 11,100 mt in 1997 to 20,500
mt in 2004, but the stock remains low relative to SSBMSY
(82,830 mt). Fully recruitedfishing mortality declined to about
0.35 in 2000 and 2001, but has since increased to 0.58 in 2004,
indicating that F continues to remain very high relative to fully
recruited F reference points (F0.1 = 0.15; Fmsy
= 0.23; Fmax = 0.27). Thus, the stock remains in an overfished
condition and overfishing continues to occur.
Total commerciallandings of Georges
Bank cod in 2005 were estimated to be a record-low 3,048 mt, 33%
lower than in 2004 (Table
1.11 Data]). Since 1978 the USA fleet landed has landed
an average 75% of the total landings and the Canadian fleet has
landed the remaining 25%. USA cod landings are generally highest
in the second calendar quarter (April-June) and are taken predominantly
from the western part (SA 521-522, 525-526, 537-539, and Subarea
6) of Georges Bank throughout the year (Figure
1.1). The majority of the landings from the eastern part (SA
561-562) of Georges Bank are taken in the first and second calendar
quarters (January to June). The Canadian fishery for Georges Bank
cod is open in January, and then June to December, with the majority
of the landings taken in the third calendar quarter (July-September).
Prior to 1994, USA landings were
taken primarily by otter trawl gear, accounting for 85% of the landings.
Since 1994, otter trawl gear account for 65% of the landings; the
recent decline in otter trawl landings is attributed to the increase
in gillnet (17%) and line trawl (17%) landings. The majority of
Canadian landings have been taken by longline gear since 1996 (Gavaris
et al. 2006).
Cod landings from Georges
Bank, categorized by size as 'scrod' (small), 'market' (medium),
and 'large', continue to be dominated by 'market' cod in both weight
and number in recent years. Historically, 'market' cod have accounted
for 37-67% of the landings by weight. Market cod are generally dominated
by fish aged 3 or 4 years old, and will vary with the strength of
incoming year classes. The most recent strong year classes that
have supported the fishery occurred in 1996 and 1998 (Figure
NEFSC spring and autumn catch
per tow biomass indices show similar trends throughout the time
1.13 Data]). Total biomass indices were relatively
stable between 1963 and 1971, increasing to a record high in 1973,
and then generally declining over the next two decades, reaching
record low levels between 1991 and 1994. The indices have improved
slightly since 1994 and have fluctuated with no trend. Both the
spring and autumn indices remained below average in 2005. Autumn
survey abundance indices for both ages 1 and 2 indicate above-average
recruitment of the 1965, 1966, 1971, 1975, 1977, 1980, 1985, and
1988 year classes (Figure
1.14 Data]). The magnitude of an above-average
year class has been declining over time, particularly noticeable
in the recruits at age 2.
Average (ages 4-8, unweighted) fishing mortality
gradually increased during 1978-1994 to a maximum of 1.5 (67%
exploitation) and has since declined to 0.24 (19% exploitation)
in 2004 (Figure
1.15 Data]). Spawning stock biomass declined
from about 93,000 mt in 1980 to a record low of 17,340 mt in 1995
and then slowly increased to 30,000 mt by 2001, primarily due
to the growth of the 1996 and 1998 year classes(Figure
1.16 Data]). The 2004 estimate of SSB was 22,564
mt, a decrease of 25% from 2001, the last year the 1996 year class
dominated the SSB. The 2004 estimate is, however, an increase
of 30% from the record low 1995 estimate.
Since 1978, recruitment at age 1 has ranged
from 2 million (2002 year class) to 43 million (1985 year class)
1.16 Data]). The 2004 year class is estimated to be
about 10.4 million fish at age 1, below the long term (1978-2004)
arithmetic average of 14.7 million age 1 fish. The 2003 year class,
however, is estimated to be 21.2 million age 1 fish, well above
the long term average. The previous above average year class occurred
in 1990 (17.8 million age 1 fish). The 1998 year class (12.8 million
age 1 fish), although below average, was the strongest since 1990.
The 1994, 2001, and 2002 year classes are the poorest of the 28-year
Yield and spawning stock biomass biological
reference points (Figure
1.17 Data])were last calculated
by the Working Group on Re-Evaluation of Biological Reference
Points for New England Groundfish (NEFSC 2002a) using data from
the 2001 assessment (O’Brien and Munroe 2001) and are the
same as those applied and reported in the 2002 and 2005 GARM assessments
(NEFSC 2002b, 2005; O’Brien et al. 2002, 2005). These are
provided in Table 1.4.
The relationship between spawning stockbiomass
and recruitment for Georges Bank cod over the period covering
the 1978-2004 year classes is illustrated in (Figure
1.18 Data]). In the last decade, low recruitment
at age 1 has generally been associated with low SSB in contrast
to the earlier time period (1978-1990) when higher recruitment
was realized from higher SSB. The most recent levels of SSB and
recruitment occur in the lower left portion of the plot illustrating
the emergence of the above average 2003 and the average 2004 year
classes from the same relatively low spawning stock. The solid
horizontal line indicates the geometric mean recruitment over
the same period. Survival ratios, recruits per unit of spawning
1.19 Data]) also illustrate the relatively high
survival of the 1985, 1992, and 1998 year classes in addition
to the 2003 year class.
MSY-based reference points were last calculated
by the Working Group on Re-evaluation of Biological Reference
Points for New England Groundfish (NEFSC 2002a) using data and
results from the 2001 assessment (O’Brien and Munroe 2001).
A complete description of the approach is given in O’Brien
et al. (2006) and NEFSC (2002a). The MSY-based reference points
calculated using this method are given in Table
1.4. The MSY estimate includes commerciallandings only and
does not include recreational landings or discards
Georges Bank cod biomass indices derived
from research surveys indicate that the stock remains below the
long term average of the 43 year time series. Fishing mortality
has been steadily declining since 1997, except for a slight increase
in 2001, and is currently at the lowest level in the time series.
Spawning stock biomass reached a record low in 1995 and slowly increased,
due to the growth of the 1996 and 1998 year classes; however, since
2001 SSB has been declining. SSB in 2004 was 22,600 mt ton, 10%
of SSBMSY. Thus, Georges Bank Atlantic cod are considered
overfished and overfishing is occurring.
1.3 Recreational and commercial landings
of Georges Bank cod (thousand metric tons).
Collette, B.B. and G.
Klein-MacPhee (editors). 2002. Bigelow and Schroeder's Fishes of
the Gulf of Maine. Smithsonian Institution Press, Washington, D.C.
Gavaris, S., L.O'Brien, B.Hatt, and K.Clark 2006. Assessment of
Eastern Georges Bank Cod. TRAC Reference Document - 2006/05; 48p.
Lough, R. G. 2004. Essential Fish Habitat Source Document: Atlantic
Cod, Gadus morhua, Life History and Habitat Characteristics.
2nd ed. November 2004. NOAA Technical Memorandum NMFS-NE-190, vi
+ 94 p.
Mayo, R. K., E. M. Thunberg, S.
E. Wigley, and S. X. Cadrin. 2002. The 2001 Assessment of the Gulf
of Maine Atlantic Cod Stock. Northeast Fisheries Science Center
Reference Document 02-02, 154 p.
Mayo, R. K and L. Col. 2002. Gulf
of Maine Cod, p123-145. In: Assessment of 20 Groundfish Stocks through
2001. A Report of the Groundfish Assessment Review Meeting (GARM),
Northeast Fisheries Science Center Reference Document 02-16.
Mayo, R. K and L. Col. 2005. Gulf
of Maine Cod, p153-184. In: Assessment of 19 Northeast Groundfish
Stocks Through 2004. 2005 Groundfish Assessment Review Meeting (2005
GARM), Northeast Fisheries Science Center, Woods Hole, Massachusetts,
15-19 August, 2005. by R. K. Mayo and M. Terceiro, editors. Northeast
Fisheries Science Center Reference Document 05-13.
Mayo, R.K. and L. Col. 2006. The
2005 Assessment of the Gulf of Maine Atlantic Cod Stock. Northeast
Fisheries Science Center Reference Document 06-02, 109 p.
NEFMC 1998. Evaluation of Existing
Overfishing Definitions And Recommendations for New Overfishing
Definitions To Comply with the Sustainable Fisheries Act. Report
of the Overfishing Definition Review Panel.
NEFSC 2002a. Final Report of the
Working Group on Re-Evaluation of Biological Reference Points for
New England Groundfish. Northeast Fisheries Science Center Reference
Document 02-04, 254 p.
NEFSC 2002b. Assessment of 20
Northeast Groundfish Stocks Through 2001. Groundfish Assessment
Review Meeting (GARM), Northeast Fisheries Science Center, Woods
Hole, Massachusetts, October 8-11, 2002 . Northeast Fisheries Science
Center Reference Document 02-16.
NEFSC 2005. Assessment of 19 Northeast
Groundfish Stocks Through 2004. 2005 Groundfish Assessment Review
Meeting (2005 GARM), Northeast Fisheries Science Center, Woods Hole,
Massachusetts, 15-19 August, 2005, by R. K. Mayo and M. Terceiro,
editors. Northeast Fisheries Science Center Reference Document 05-13.
O’Brien, L., J. Burnett,
and R. K. Mayo. 1993. Maturation of Nineteen Species of Finfish
off the Northeast Coast of the United States, 1985-1990. NOAA Tech.
Report. NMFS 113, 66 p.
O’Brien, L. 1998. Factors
influencing rates of maturation in the Georges Bank and Gulf of
Maine Atlantic cod stocks. Northwest Atl. Fish. Organ. (NAFO) Sci.
Counc. Res. Doc. No. 98/104. 34 p.
O'Brien, L. and N. J. Munroe 2001.
Assessment of the Georges Bank Atlantic cod stock for 2001. Northeast
Fisheries Science Center Reference Document 01-10:126.
O’Brien, L., N.J. Munroe,
and L. Col. 2002. A. Georges Bank Atlantic Cod in: Assessment of
20 Northeast groundfish stocks through 2001. A Report of the Groundfish
Assessment Review Meeting (GARM), Northeast Fisheries Science Center,
Woods Hole, Massachusetts, October 8-11, 2002. Northeast Fisheries
Science Center Ref. Doc. 02-16: 522.
O’Brien, L., R. G. Lough,
R. K. Mayo, and J. J. Hunt. 2005a. Gulf of Maine and Georges Bank
(NAFO Subareas 5 and 6). In: K. Brander, ed. Spawning and life history
information for North Atlantic cod stocks. ICES Cooperative Research
Report No. 274, 152 p.
O’Brien, L., N.J. Munroe,
and L. Col. 2005b. A. Georges Bank Atlantic Cod in: Assessment of
19 Northeast groundfish stocks through 2004. 2005 Groundfish Assessment
Review Meeting (2005 GARM), Northeast Fisheries Science Center,
Woods Hole, Massachusetts, August 15-19, 2005. Northeast Fisheries
Science Center Reference Document 05-13: 508.
O'Brien, L., N.Shepherd, and L.
Col. 2006. Assessment of the Georges Bank Atlantic cod stock for
2005. Northeast Fisheries Science Center Reference Document. 06-10:148.
Pentilla, J. and V. M. Gifford.
1976. Growth and Mortality Rates for Cod from the Georges Bank and
Gulf of Maine Areas. Int. Comm. Northw. Atl. Fish. Res. Bull. No.
Serchuk, F. M., M. D.
Grosslein, R. G. Lough, D. G. Mountain, and L. O’Brien. 1994.
Fishery and environmental factors affecting trends and fluctuations
in the Georges Bank and Gulf of Maine Atlantic cod stocks –
an overview. ICES Mar. Sci. Symp. 198: 77-109.